The reutilization of granite sludge generated in granite cutting and processing possesses economic and ecological benefits. In this study, high-strength glazed glass-ceramics were prepared entirely from granite powder using dense sintering and instantaneous glaze firing. The densification and glaze formation are clarified in terms of phase evolution to study their effects on the flexural strength and surface glossiness of the glass-ceramics. The milling process promotes particle refinement and the removal of colored minerals, thus increasing the powder whiteness and sinterability. After dense sintering at 1100 degrees C, instantaneous glaze firing at high temperatures decreases the flexural strength while greatly increases the surface glossiness of the glass-ceramics due to the dissolution of quartz and feldspars in the liquid phase. After the acid-leached powder was densely sintered and fired with a rapid heating of 50 degrees C/min to 1300 degrees C, the pinhole-free glazed glass-ceramic has a flexural strength of 112.5 MPa and a surface glossiness of 54.7 GU (glossiness unit), meeting the quality requirements of the bright glazed tiles in the market. The stepwise sintering process provides a simple processing route for recycling granite sludge into decorative construction tiles and high-temperature glazes, promising the scalable and value-added utilization of granite sludge.
The effects of Sc and/or excess Mg on the microstructure characteristics, tensile properties, and fracture behavior of a hypoeutectic Al-10Mg2Si alloy were systematically studied. The results showed that adding 0.25
利用放电等离子烧结(Spark plasma sintering,简称SPS)技术并配合机械加工的方式制备了 3种相对摩擦工作面石墨取向为0°、45°和90°的铜基粉末冶金摩擦材料.采用MM1000-Ⅱ型惯性制动试验台测试了 3种材料的制动摩擦磨损性能,并对其试验后的摩擦表面三维形貌特征、近摩擦面区域特征、磨屑特征和摩擦表面物相进行分析,研究了石墨排列取向对不同制动条件下铜基粉末冶金材料摩擦磨损性能的影响.结果表明:与石墨取向为0°比,石墨取向为45°和90°均摩擦系数均呈现先上升后下降的趋势;在相同的制动条件下,石墨取向为45°的平均摩擦系数与石墨取向为0°的材料相差不大,但磨损率较低,特别是0.8 MPa、250 km/h条件下石墨取向为90°的材料的磨损率仅为石墨取向为0°的材料的31.8％.提高制动初速度均能够促进3种材料摩擦表面形成氧化膜,对于石墨取向为0°的材料,表面形成以Fe3O4为主的氧化膜,而对于石墨取向为90°的材料,则形成以Fe2O3为主的氧化膜.
采用扫描电镜(SEM)、电子背散射衍射(EBSD)技术和室温拉伸测试等研究了 Nb、V、Ti微合金化元素对20MnSi钢显微组织和力学性能的影响.结果表明:Nb、V、Ti微合金化及其所形成的第二相粒子可以阻碍试验钢的晶界迁移、细化晶粒尺寸,经热轧-空冷后晶粒明显细化,晶粒尺寸可达12级,综合力学性能明显优于20MnSi穿水钢筋,并达到新国标中400 MPa级钢筋所要求的性能指标.根据理论模型计算,晶界强化、固溶强化和位错强化增量分别约占屈服强度的54％、22％和17％,而由于微合金化元素含量较低且所形成的第二相粒子体积分数较低,析出强化增量在试验钢屈服强度中的占比仅约7％,表明Nb、V、Ti微合金化设计而导致的晶粒细化对试验钢力学性能提升所产生的贡献十分显著.
采用光学显微镜(OM)、透射电镜(TEM)及有限元分析(FEA)等研究了轧制工艺对Fe-0.2C-1.45Mn-Nb-V-Ti钢板厚方向的组织和力学性能均匀性的影响.结果表明:在压缩比受限的条件下,利用奥氏体晶界促进形核的机制(即边界诱导相变机制,BIT机制)可以达到细化晶粒的目的,试验钢的平均晶粒尺寸均小于10 μm;结合温度与累计应变的反向分布特点和轧制工艺的优化,轧制63 mm厚的试样表面和中心晶粒尺寸偏差小于2μm,有效改善了晶粒尺寸沿板厚方向的偏差.在本文的轧制工艺下,提高了厚板沿厚度方向的组织均匀性,获得了优异的力学性能.
